Dry ice used by mechanized boats to preserve fish and dumped in the river over a long period of time can harm more marine life than the little it seeks to preserve on the shelf.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/dumping-dry-ice-rivers-killing-marine-life-expert-panel
[2] http://admin.indiaenvironmentportal.org.in/category/author/paul-fernandes
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-goa
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/goa
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/marine-ecosystems
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/river-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/marine-life
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/waste-disposal
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/biodiversity
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/state-pollution-control-board-spcb-0
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/environment